This post is largely inspired by a post by a friend of mine that inspired me to start writing reviews and summaries of (nonfiction) books I read.

I just finished reading Influence: The Psychology of Persuasion by Robert Cialdini. I picked up the book after seeing it mentioned several times on Hacker News and Reddit, the irony of which didn't dawn on me until I had finished the book. The genre of accessible books on results in experimental psychology has been a favorite of mine since reading one of my favorite books, Thinking, Fast and Slow, and this book did not disappoint.

The subject matter of Influence is the "weapons of influence" used by what Cialdini calls compliance professionals - salespeople, politicians, and anyone else who can benefit from manipulating people into compliance. More generally, it explores shortcuts or weaknesses in all of our minds that can be exploited to get us to agree to something without giving it full thought. As evidenced by the testimonials on the dust jacket (also slightly ironic given the results within), the book is very interesting to marketing and sales professionals, but it also has value for anyone looking to make better decisions about pretty much anything that someone might talk you into. I've included my chapter-by-chapter summary below, along with some commentary of my own.

One interesting thing about the results that I didn't find in the book is that, at least in a sales setting, some of the "weapons" apply at different times than others. For example, "social proof" is largely used to influence people near the top of the funnel, while "scarcity" is largely used as a closing tactic. It would be interesting to categorize all the results in this space in that way, and create a taxonomy of the compliance tools from the perspective of different types of persuasion - political campaigns, sales manuals, marketing strategies, religious indoctrination, the techniques of pick-up artists, etc. In other words, flip the layout of the book around and show how the different techniques are used at different layers of the processes. Future work?

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Influence: The Psychology of Persuasion

Chapter 1: Weapons of Influence

Many animals exhibit fixed-action patterns, sometimes complex patterns of behavior that are reliably activated by an often simple trigger. Mother turkeys' protective, maternal behavior is triggered by a specific "cheep-cheep" sound produced by their young; however, they can be tricked into acting motherly to a stuffed version of a natural predator with an embedded tape player that makes the same noise.

Humans have a similar response, though the mechanism is more complex and is often learned. In both cases, the behavior triggering is a shortcut of sorts, a usually-correct way to respond to a situation without cognitive load. Much of the time, the shortcut works well, but often it can be exploited or misinformed. Particularly as our daily lives become more information-rich and we are faced with more choices, these shortcuts are crucial to living happy lives. We need tools to help us understand when the shortcuts are engaged and whether we should scrutinize a decision if so. In the animal kingdom, some animals have learned to exploit the automatic response to another species' triggers; likewise, some humans (compliance professionals) exploit our automatic behavior. This is especially powerful because the results of these triggers, these weapons of influence, are usually subtle, changing our actions without our conscious knowledge.

Each of the next six chapters presents one weapon of influence in depth.

Examples and results.

• People are more likely to grant you a favor if you provide a reason; however, the reason doesn't have to be a good one, and we instead will respond to the word "because" regardless of the reason.
• People have a shortcut that tells them "expensive = good".
• The contrast principle states that if we are exposed to two items in sequence, if the second is different from the first our perception will amplify the difference. This can be used to sell by introducing an expensive item before a less expensive one - the second will seem like a deal, or for upsells where a small add-on item seems insignificant in the face of a large purchase.

Chapter 2: Reciprocation

The rule for reciprocation states that we feel obliged to repay anything another person has provided for us in a similar way. This rule is pervasive across human cultures, and the sense of obligation it creates is very hard to resist and is thus very powerful. It can overcome feelings of dislike or unwelcomeness, and it applies in all sorts of different situations.

Another aspect of the power of the rule lies in the fact that anyone can offer us a gift, creating an uninvited but powerful debt the receiver feels obligated to repay. In other words, there is an implied second rule: an obligation to receive; as a result, the power to create the feeling of debt is in the hands of others, making it easy to exploit.

There is another type of asymmetry to the rule as well. There is considerable flexibility in the obligation to return a rule "in a similar way," and this can be exploited by compliance professionals to produce better returns than the gift offered. By asking for something specific while within the time frame of the rule, a calculating individual can get a response that is much more valuable than their own outlay.

Another manifestation of the rule is the obligation to make a concession to someone who has offered one. This, combined with the contrast principle, results in a combined technique - rejection-then-retreat. In this technique, a compliance professional makes a larger request, likely to be denied, in order to set up the smaller target request. The combination of the contrast of the smaller and larger requests along with the obligation to return the concession often results in a "no" becoming a "yes". The smaller request doesn't need to be small for this to be effective. This technique makes it hard to lose - you can either sell the big ticket, or you can retreat and have a high chance of selling the small ticket. Additionally, by giving a concession in response, one will feel more responsible for and happy with an arrangement. This likely has to do with the principle of commitment and consistency in the next chapter.

The best way to protect ourselves from the rule of reciprocation is not to refuse every gift we are given. Instead, we should seek to recognize when a gift is being used as a compliance device. In those situations, we can redefine the gift as what it is - a compliance tactic - and evaluate the rest of the situation as though we would had the gift not been given.

An interesting idea is to combine rejection-then-retreat with further contrast-principle-utilizing upsells. By tacking on extra items, it may be possible to turn the small-ticket item - which the prospect now feels somewhat obligated to accept - into a large ticket sale.

The rule of reciprocation has been theorized as one of the key points in the development of sophisticated human cultures. It produces a kind of trust between individuals, allowing them to establish relationships without fear of loss.

Reciprocation seems like its best used at the crux point of a situation - at the buy decision, basically.

Examples and results.

• Christmas cards sent to random people often resulted in Christmas cards back, even though the people didn't know the sender.
• Bringing a random acquaintance a Coke resulted in the acquaintance purchasing more raffle tickets than if they didn't recieve a Coke.
• Hare Krishnas offer (push, really) a small gift, usually a flower or book before asking for donations.
• Politician back-scratching creates a sense of obligation for a future favor. Individual and corporate gifts to politications may also attempt to trigger the reciprocity rule.
• "Free samples" aren't really free - they expose the public to the product, but they can also trigger the reciprocity rule.
• Rejection-then-retreat A retreat from a denied, significant request often results in the retreat from the "no."
• Rejection-then-retreat to get the names of friends the salesman can use if a prospect doesn't want to buy.
• Watergate was (sort of) rejection-then-retreat from an earlier, more harebrained scheme.

Chapter 3: Commitment and Consistency

We feel a very strong desire to be consistent with our past actions. We are often unaware of this desire though, resulting in behavior that is outside what logic would dictate. This slavish consistency with our own actions is triggered by a commitment to a course of action, particularly a commitment we perceive as public. In a way, these commitments alter our own image of ourselves, which is a subtle force in all future actions. This quiet power, combined with the automatic nature of the consistency response, makes commitment and consistency a major tool for compliance professionals, and one that is hard to resist.

Written commitments have particularly strong power over us. In general, the more active a commitment is, the more effort required to make it, and the more public it is, the more powerful it is. In order to really internalize a commitment, we must accept it as our own behavior, which means we can't attribute it to an external force such as a large prize. By internalizing our commitments, we build additional structure to support our decisions, and this can be exploited. By initially providing and withdrawing a good reason to make a decision, compliance professionals can urge us to the decision. The key lies in providing enough time to justify the decision to ourselves for other reasons.

To avoid letting our consistency be exploited, we don't eliminate consistency - it is a valuable tool for eliminating cognitive load. Instead, we have to rely on our intuition. If we feel, deep inside, that we are being foolishly consistent we need to take the time to more carefully evaluate the situation and produce a response based on logic rather than one based on consistency.

Consistency seems like it is best used at the marketing phase, when it is the least obvious and therefore the least easy to avoid. Because its effects penetrate far into the future and result in deep internal changes, an early commitment can result in far-reaching effects. Obviously, it is also applicable later in the cycle, but the effects are easier to ward off.

Examples and results.

• American POWs during the Korean War were convinced to write anti-American or pro-Communist essays and do all sorts of things based on some sophisticated commitment mechanisms employed by the Chinese.
• Horse race bettors are more confident in the chance of their horse winning after placing a bet than before.
• A bystander was much more likely to stop a thief if asked earlier if they would watch the belongings.
• Toy manufacturers create artificial demand for specific toys around Christmas, then limit availiability until after the holidays. Promises to children result in sales later.
• Getting people to abstractly commit to charitability on the phone earlier results in much better results if asked to volunteer later.
• A commitment to driver safety resulted in a large number of people agreeing to put up a billboard in their front lawn.
• Testimonial contests encourage all who apply to believe in the product they are writing about.
• Writing down an estimate results in a much stronger commitment to it.
• Hazing rituals inspire individuals to have very strong commitment to the cause for which they are hazed (effort results in stronger commitment).
• Children will better internalize lessons that aren't accompanied by a threat (or, presumably, a reward). This may be different for different children.
• Lowball Offer a car for a low price, then wait a while, the retract the offer. People will build up their own reasons for agreeing to the purchase in the first place.
• Performing an interview that encourages the person to respond in ways favorable to the overall goal - for example, an attractive woman interviewing men about their social habits in order to sell Zagat's or something - then asking for the sale.

Chapter 4: Social Proof

The principle of social proof states that when we are confused about the best course of action, we take our cue from the actions of those around us. Like many of the other weapons, it serves a valuable purpose but becomes an issue when we respond to it automatically, regardless of other factors, such as whether the social proof is genuine or false. Often, the "social proof" we are actually getting is the result of a group of people all looking for social proof and trying to play it cool. This leads to "pluralistic ignorance," in which a whole group reads the wrong social cue. This is likely the cause of bystander inaction. The two key drivers for social proof are uncertainty, which motivates the examination of social cues in the first place, and similarity, in which we prefer to take our cues from those most similar to ourselves.

In order to best protect ourselves from false social proof is to be sensitive to when the cues we are receiving are incorrect. This can occur because the social data has been made up - such as in the case of a "man on the street" testimonial for a product - or in the case where social proof is being interpreted incorrectly in a recursive way by a growing group - as in the case of bystander inaction.

Examples and results.

• Canned laugh tracks are attempting to make you laugh via social proof.
• Bartenders throwing a couple bucks in the tip jar at the beginning of the night.
• Advertising and marketing techniques claiming things are 'fastest growing' or the like and man-in-the-street interviews and testimonials are meant to engage the principle of social proof.
• Children who see other children playing with dogs are way less likely to be scared of dogs, even if they see the other children in a video.
• Pluralistic ignorance When a group of people are all attempting to read social cues but end up reading everyone else playing it cool while they try to read the crowd.
• Bystander inaction is an example of pluralistic ignorance: everyone is trying to evaluate the situation, but mistakenly reads the others' calmness as indicating that the situation is fine.
• Three-person groups are less likely to report a likely fire than individuals, particularly if the group contained people instructed to ignore the smoke.
• Uncertainty triggers the need for social proof: when someone is clearly hurt, people almost always help even if it is dangerous; however if it is unclear that there is an emergency, far fewer people help when there are other people not helping.
• To get help in a crowd, single someone out, tell them you need help and ideally tell them what help you need.
• Similarly: school anti-smoking efforts are much more effective if lead by peers.
• Werther effect Public evidence of a suicide, such as reporting in papers or the news, results in other people committing suicide. The imitation suicides are often committed by people similar to the original victim. This may also be true of homocides.
• Cult suicides are often rooted in social proof. The People's Temple suicides were thought to be largely a result of Jim Jones moving the cult to Guyana, making the only similar people around the cultists themselves.
• Claques are groups of opera-goers that are paid to applaud - canned applause for live shows.
• Traffic jams are sometimes caused by two drivers signalling to get over, which drivers behind interpret as social proof of a lane blockage further up.

Chapter 5: Liking

Unsurprisingly, we are more likely to comply with the requests of people we like. This liking can take the form of friendship or another existing relationship, or it may be as simple as one of a number of factors that cause liking quickly and reliably without the development of a deeper relationship. These factors include physical attractiveness (how good looking is the person?), similarity (in what ways is the person like us?), compliments (how much does the person seem to like us?), contact (how familiar are we with the person or the request?), cooperation (how much help have we given this person?), and conditioning / association (what other things is this person or request like? what are they associated with and how do I feel about those things?).

Compliance professionals leverage our close relationships to gain compliance via association with our friends and family. They also leverage the factors above by making us like them in order to tap into those feelings. In order to resist the automatic effect of these feelings of liking, we need to notice when we are liking someone more than we would expect, or when that liking is being inspired in the context of a compliance request. The stronger the feeling, the more wary we should be. Once we notice the feeling, we must try to distance our liking from the compliance request in order to make the best possible decision.

Examples and results.

• Tupperware parties and their ilk leverage our friendships to sell products.
• Halo effects When one positive characteristic of a person or thing dominates the perception of that person or thing.
• Example of attractiveness: attractive candidates got more than twice as many votes as unattractive ones, but the voters didn't think the appearance of the candidates mattered to them.
• Attractive criminals receive lighter sentences than ugly ones.
• Example of similarity: Studies show that we are more likely to help people who dress like us. Another: salespeople find similarities with us in our background or interests.
• Typically people prefer a photo of themselves that is flipped horizontally because it matches their image of themselves - the one they see in the mirror every morning.
• In contrast to the contact theory, school desegregations often result in negative race relationships because of the nature of the environment. However, forming cooperative groups in which students of different races work together has promising results (cooperation vs. contact).
• Good cop / bad cop works on several principles: contrast and liking.
• Example of association: people often personally dislike the weatherman for delivering bad weather news. Another: (presumably straight) men who see car ads with good looking women thing the car is faster, better looking, and better designed.
• People perceive things as more favorable while they are eating.
• Sports fanaticism can be seen as a case of trying to associate onesself with the city or team's success; likewise, sports fans distance themselves from recently unsuccessful teams.

Chapter 6: Authority

We all have a ingrained feeling that we have a duty to authority. This feeling is very powerful, and applies to situations where, as outsiders, we would never think it would, such as inflicting pain to others. Furthermore, this feeling of duty is very robust, and persists even when obedience clearly means doing things we find distasteful. Interestingly, the actual authority is less important than the perceived authority. In other words, we respond to people in doctors coats, not to the MD. Titles, dress, and other trappings of authority (expensive cars, uniforms, etc.) all play into this sense of authority.

Resisting this effect is complicated, as, like many of the weapons of influence, it often happens without us noticing, and we are often unaware of how powerful its force is. Additionally, it often provides the correct information - doctors, lawyers, and the like often have guidance that is better than our own. The trick is to first carefully evaluate when we are dealing with real authority. If the authority is false, we can react accordingly. If it is real, we need to evaluate how likely it is that the authority is dealing with us truthfully. We can use other information and our own intuition to make this evaluation.

Examples and results.

• Milgrim experiments Under a wide variety of conditions, people were willing to inflict pain on other people when prompted by an authority figure.
• Brian Wilson laid on railroad tracks to protest shipment of weapons to Nicaragua; the soldiers running the train ran over him.
• Trained nurses will often follow the directions of a doctor, even if it's on the phone and the request flies in the face of their training.
• Sanka advertisements use an actor who portrayed a doctor to extol the benefits of decaf coffee.
• This that are important are perceived as being larger; the reverse also holds true.
• People on the street are more likely to comply with an odd request if the requester is dressed in a guard uniform.
• People are less likely to honk at bad drivers in nice cars.

Chapter 7: Scarcity

The perceived value of an opportunity is inversely proportional to its availability. In general, loss is more motivating than gain; for each person, the multiple is different, resulting in a spectrum of risk-oriented behavior. Both first-order (how rare is X?) and second-order (is X becoming rarer?) scarcity affects our perception. Compliance professionals can artificially limit availability or create the perception of limited availability to gain our compliance. Alternatively, they can create deadlines for an opportunity in order to take advantage of our scarcity response.

The theory of psychological reactance posits that the loss (or impending loss) of our freedoms increases our desire for those freedoms and associated goods and services. This may be the source of the "terrible twos" in which toddlers can't seem to be satisfied: any change in their state results in some perceived loss of freedom. This also may be the cause of hoarding in response to limits imposed on ownership of an object (e.g., incandescent bulbs fairly recently). This type of hoarding also extends to censorship - the limiting of free access to information - and to judges' instructions to disregard certain evidence presented. The combination of this information scarcity with opportunity scarcity is a powerful compliance tactic: let the mark know that the information about the scarcity of the opportunity is itself limited, insider information.

Evidence suggests that combined first- and second-order scarcity produces a stronger response than either alone. Specifically, things that are newly scarce are perceived as being more desirable than things that have been scarce for some time. Another condition that heightens a feeling of scarcity is when the scarcity is caused by an observable demand. In other words, when we see the demand that is causing the scarcity, we desire the opportunity more.

To escape our scarcity response, we must first identify the increase of desire caused by scarcity. When we find ourselves in that situation, we need to consciously distance ourselves from the desire to possess the item and evaluate the intrinsic value of the item instead.

Because of the short-term effects of scarcity, it seems like it is most applicable in the 'close' phase of a transaction, after the initial interest but while the item is still being evaluated.

Examples and results.

• The desire to answer a phone call when someone is physically with you is the scarcity principle at work.
• Collectibles are often valued on their scarcity; arguably the whole joy of collection is in possessing scarce items.
• "Limited number" and "limited time offer" are both compliance tactics utilizing scarcity.
• Psychological reactance We react to the loss of behavioral freedoms by desiring to perform the limited behaviors.
• Toddlers prefer toys that are blocked by an obstacle.
• Romeo and Juliet is an example of scarcity in effect - the parental direction to end their affair strengthened their desire for it.
• After limiting a certain kind of detergent in Florida, residents hoarded it. Additionally, they rated it as better than other detergents.
• Hearing that a speech proposing a certain topic would be banned, more students supported the topic itself.
• Young people seeing an age-restricted book desired it more and thought they would like it more than the non-age-restricted version.
• A UChicago Law School study found that jurors awarded more to a woman injured by a careless driving defendant if the defendant had insurance - and yet more if they were told to disregard that he had insurance.
• A study had participants rate cookies under several conditions; scarcer conditions produced better ratings in this order (least to best average rating):
  • Ten cookies in the jar
  • Two cookies in the jar
  • Ten cookies in the jar, but then eight were removed in front of the participant, saying the experimenter had made a mistake
  • Ten cookies in the jar, but then eight were removed in front of the participant, saying that the other participants needed them
• Riots often result from degrading conditions, not necessarily bad ones - race riots, Gorbachev's coup, etc.
• Bringing in a second buyer - real or not - often motivates the sale of a scarce resource (homes, appliances, cars, etc.)

Epilogue: Instant Influence

A common theme in all the weapons of influence is that we often make decisions based on a very limited subset of the information we have. Unfortunately, our modern lives all but require us to do this to function at a normal level. All signs indicate that this frantic pace is increasing rather than decreasing, which means we need to be ever more reliant on these shortcuts. Unfortunately, these shortcuts can be exploited by people playing outside of the rules of safe evaluation. In this case, we should actively counter-attack: don't buy products leveraging these weapons in an unfair way; boycott television that uses canned laughter; don't vote for politicians that exploit us. We need our shortcuts to survive, and we need to out and ultimately stop those who would exploit them.